Police in Ethiopia have uncovered a grave containing at least 200 bodies along the border between the strife-torn Oromiya and Somali regions, state-affiliated media said.

The mass grave was found during an investigation of a former administrator of the Somali region who is facing trial on charges of human rights abuses and stoking clashes, the Fana Broadcasting Corporation said late on Thursday, quoting police officials.

It did not give further details.

Abdi Mohammed Omer was forced to resign on August 6 and was arrested weeks later after violence broke out in the provincial capital, Jijiga.

Rights groups have routinely accused his administration of abuses such as torture, while some witnesses claimed he had ordered paramilitary raids on civilians in neighbouring Oromiya province after ethnic clashes there last September.

The region has been plagued by violence for decades as the government fought the secessionist Ogaden National Liberation Front before both sides signed a peace deal last month.